Solvent-Free Stereoselective Synthesis of (E)-Trifluoromethyl Imines and Hydrazones

Abstract

A new, green and efficient strategy for the synthesis of trifluoromethyl ketimines, aldimines, and hydrazones starting from the corresponding trifluoromethyl carbonyl compounds or their hemiacetals is reported. The condensation reactions were performed under solvent-free conditions with a range of amines or hydrazines and proceeded with high stereoselectivity, always giving only the E-isomer in very good yields.

fluorinated compounds - imines - hydrazones - stereo­selectivity - condensation

References

1 Fluorine in Medicinal Chemistry and Chemical Biology   Ojima I. Wiley; Chichester: 2009. 

2 Prakash GKS. Paknia F. Vaghoo H. Rasul G. Mathew T. Olah GA. J. Org. Chem.  2010,  75:  2219 

3 Begue J.-P. Bonnet-Delpon D. Crousse B. Legros J. Chem. Soc. Rev.  2005,  34:  562 

4 Török B. Abid M. London G. Esquibel J. Török M. Mhadgut SC. Yan P. Prakash GKS. Angew. Chem. Int. Ed.  2005,  44:  3086 

5a Creary X. J. Org. Chem.  1987,  52:  5026 

5b Gosselin F. O’Shea PD. Roy S. Reamer RA. Chen C.-Y. Volante RP. Org. Lett.  2005,  7:  355 

6a Barney CL. Huber EW. McCarthy JR. Tetrahedron Lett.  1990,  31:  5547 

6b Gulevich AV. Shevchenko NE. Balenkova ES. Röschenthaler G.-V. Nenajdenko VG. Tetrahedron  2008,  64:  11706 ; and references therein

7 Abid M. Savolainen M. Landge S. Hu J. Prakash GKS. Olah GA. Török B. J. Fluorine Chem.  2007,  128:  587 

8a Fioravanti S. Pellacani L. Ramadori F. Tardella PA. Tetrahedron Lett.  2007,  48:  7821 

8b Colantoni D. Fioravanti S. Pellacani L. Tardella PA. J. Org. Chem.  2006,  71:  6295 

8c Colantoni D. Fioravanti S. Pellacani L. Tardella PA. Org. Lett.  2004,  6:  197 

9 Fioravanti S. Pellacani L. Tardella PA. Vergari MC. Org. Lett.  2008,  10:  1449 

10 Gong Y. Kato K. J. Fluorine Chem.  2001,  108:  83 

11a Molteni M. Volonterio A. Zanda M. Org. Lett.  2003,  5:  3887 

11b Iwata S. Ishiguro Y. Utsugi M. Mitsuhashi K. Tanaka K. Bull. Chem. Soc. Jpn.  1993,  66:  2432 

12 Soloshonok VA. Yasumoto M. J. Fluorine Chem.  2007,  128:  170 ; and references therein

13 Soloshonok VA. Ono T. J. Org. Chem.  1997,  62:  3030 

14 Crousse B. Bonnet-Delpon D. In e-EROS: Encyclopedia of Reagents for Organic Synthesis   Wiley; New York: 2005. DOI: 10.1002/047084289X.rn00560

15a Fuchigami T. Nakagawa Y. Nonaka T. Tetrahedron Lett.  1986,  27:  3869 

15b Neugebauer FA. Umminger I. Chem. Ber.  1982,  115:  3706 

15c Tanaka K. Maeno S. Mitsuhashi K. Chem. Lett.  1982,  543 

16a Funabiki K. Nagamori M. Matsui M. Enders D. Synthesis  2002,  2585 

16b Enders D. Funabiki K. Org. Lett.  2001,  3:  1575 

17 Yeh HJC. Ziffer H. Jerina DM. Boyd DR. J. Am. Chem. Soc.  1973,  95:  2741 

18 Kanai M. Ueda MKK. Yasumoto M. Kuriyama Y. Inomiya K. Ootsuka T. Katsuhara Y. Higashiyama K. Ishii A. J. Fluorine Chem.  2005,  126:  377 

19 Ros A. Díez E. Marqués-López E. Martín-Zamora E. Vázquez J. Iglesias-Sigüenza J. Pappalardo RR. Álvarez E. Lassaletta JM. Fernández R. Tetrahedron: Asymmetry  2008,  19:  998 

20a Tanaka K. Maeno S. Mitsuhashi K. J. Heterocycl. Chem.  1985,  22:  565 

20b Hegarty AF. Cashman MP. Scott FL. J. Chem. Soc., Perkin Trans. 2  1972,  1381 

21

The synthesis of 19 under solvent-free conditions gave the expected product in very low yields, probably because
p-nitrophenylhydrazine is a solid compound.

22 Zhang W. Green Chem.  2009,  11:  911 

23 An efficient, although not stereoselective, synthesis of α-fluoroimines was very recently reported starting from α-fluoroketones, see: Malamakal RM. Hess WR. Davis TA. Org. Lett.  2010,  12:  2186